Help needed ! My dad has a Baxi WM 40/3 OF . The rads come on when we need hot water only. We only have a complicated installation manual. The dials on the rads don't turn. Don't think they ever did.
Under the water tank there is a yellow plastic clip on tag that says heat on / heat off. Around a copper pipe. The valve turns easy when I unclipped the tag, turned to heat off & got hot water only. Result!
Until a electrician friend said you must Never Touch a Yellow Tag. It's there to stop you turning the valve.
I have googled for a couple of hours and cannot find any image or note about this valve or yellow plastic tags.
I've never had central heating. My late mum knew the instructions.